Re: [PATCH] virtio-blk: emit udev event when device is resized

Rusty Russell
2013-02-27T01:52:32Z

Milos Vyletel <milos.vyletel@sde.cz> writes:

> When virtio-blk device is resized from host (using block_resize from QEMU) emit
> KOBJ_CHANGE uevent to notify guest about such change. This allows user to have
> custom udev rules which would take whatever action if such event occurs. As a
> proof of concept I've created simple udev rule that automatically resize
> filesystem on virtio-blk device.
>
> ACTION=="change", KERNEL=="vd*", \
> ENV{RESIZE}=="1", \
> ENV{ID_FS_TYPE}=="ext[3-4]", \
> RUN+="/sbin/resize2fs /dev/%k"
> ACTION=="change", KERNEL=="vd*", \
> ENV{RESIZE}=="1", \
> ENV{ID_FS_TYPE}=="LVM2_member", \
> RUN+="/sbin/pvresize /dev/%k"
>
> Signed-off-by: Milos Vyletel <milos.vyletel@sde.cz>

OK, I collapsed the event[] line as suggested by Asias, and applied this.

Thanks,
Rusty.

From: Milos Vyletel <milos.vyletel@sde.cz>
Subject: virtio-blk: emit udev event when device is resized

When virtio-blk device is resized from host (using block_resize from QEMU) emit
KOBJ_CHANGE uevent to notify guest about such change. This allows user to have
custom udev rules which would take whatever action if such event occurs. As a
proof of concept I've created simple udev rule that automatically resize
filesystem on virtio-blk device.

ACTION=="change", KERNEL=="vd*", \
ENV{RESIZE}=="1", \
ENV{ID_FS_TYPE}=="ext[3-4]", \
RUN+="/sbin/resize2fs /dev/%k"
ACTION=="change", KERNEL=="vd*", \
ENV{RESIZE}=="1", \
ENV{ID_FS_TYPE}=="LVM2_member", \
RUN+="/sbin/pvresize /dev/%k"

Signed-off-by: Milos Vyletel <milos.vyletel@sde.cz>
Tested-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (minor simplification)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 8ad21a2..922bcb9 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -539,6 +539,7 @@ static void virtblk_config_changed_work(struct work_struct *work)
struct virtio_device *vdev = vblk->vdev;
struct request_queue *q = vblk->disk->queue;
char cap_str_2[10], cap_str_10[10];
+ char *envp[] = { "RESIZE=1", NULL };
u64 capacity, size;

mutex_lock(&vblk->config_lock);
@@ -568,6 +569,7 @@ static void virtblk_config_changed_work(struct work_struct *work)

set_capacity(vblk->disk, capacity);
revalidate_disk(vblk->disk);
+ kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
done:
mutex_unlock(&vblk->config_lock);
}